Cross-belt magnetic separator



Nov. 22, 1955 K. A. BLIND 2,724,504

CROSS-BELT MAGNETIC SEPARATOR Filed Feb. 19, 1953 INVENTOR.

WQEW

22 MWEMW United States Patent CROSS-BELT MAGNETIC SEPARATOR Kari A.Blind, Thiensville, Wis., assignor to Dings Magnetic Separator Co.,Milwaukee, Wis., a corporation of Wisconsin Application February 19,1953, Serial No. 337,849

8 Claims. (Cl. 209223) The present invention relates generally toimprovements in the art of magnetic separation, and relates moreparticularly to improvements in the construction and operation ofelectrically energized magnetic separators of the cross-belt typewherein mixed granular magnetic and non-magnetic particles aretransported by a main conveyor deck through a magnetic field and themagnetic particles are withdrawn from the mixture by magnetic influenceand are removed by an auxiliary conveyor deck travelling transversely ofthe path of the main conveyor.

The primary object of my present invention is to provide improved meansfor energizing the magnet of an electro-magnetic cross-belt separator sothat most effective removal of the magnetic particles will beaccomplished.

It has heretofore been common commercial practice to utilize so-calledcross-belt separators for removing magnetic particles from bulk mixturesof granular magnetic and non-magnetic materials while being transportedin the form of a relatively thin layer through a magnetic field betweenmain and auxiliary conveyor decks travelling transversely of each other.In some of these prior separators the magnetic separating zone or fieldis disposed within a magnetic loop having complementary internal magnetpoles one of which has a flat pole face located beneath the mainconveyor while the other has a single or multiple wedge-shaped pole facedirectly above the auxiliary conveyor, and wherein the wedge pole isembraced by electric energizing windings for the entire magnet disposedremote from its wedge face.

In order to insure most efficient separation of the mag neticingredients from the mixture, it is necessary to concentrate the fluxlines spanning the magneticseparating zone or gap between thecomplementary polefaces, near the apex of each wedge, and it hasheretofore been proposed to utilize pole tips for the wedge face orfaces formed of special materials such as cobalt alloy. While thisprocedure improves the flux concentration to some extent, it isdiflicult and costly to construct such wedge poles, and I have foundthat a far greater and more satisfactory concentration of these fluxlines is obtainable by surrounding or embracing the wedge tip with anelectric energizing winding or coil which is disposed near the wedgeapex and closely adjacent to the auxiliary conveyor deck which removesthe separated magnetic particles.

.It is therefore an important object of the present invention to improvethe concentration of flux lines within the most effective area of theseparating zone of a crossbelt magnetic separator, by locating a portionof the electro-magnet energizing winding about the apex or apices of thewedge face or faces of the magnetic particle removing magnet closelyadjacent to the separating zone.

Another important object of the invention is to enhance the efficiencyof the separating magnet of an electromagnetic cross-belt separatorhaving a wedge shaped pole face, by more effectively applying themagnetomotive force with the aid of additional ampere turns located asnear as possible to the apex of the wedge.

2,724,504 Patented Nov. 22, 1955 Still another important object of thisinvention is to provide an improved electro-magnet assemblage forcrossbelt magnetic separators which will most effectively concentratethe flux within the separating zone so as to insure maximum separationof the magnetic particles without necessarily providing wedge-shapedpole tips formed of special metals.

These and other more specific objects and advantages of the inventionwill be apparent from the following detailed description from which itwill be noted that the gist of my invention is the provision of across-belt magnetic separator comprising a magnet having complementarypoles between which transversely movable conveyor decks travel through amagnetic field or separating zone, and wherein one pole has a flat facecooperating with one of the decks at one side of the zone of separationwhile the other pole has a wedge face cooperating With the other deck onthe opposite side of the zone and the magnet is energized by electricwindings embracing the wedge pole and surrounding the wedge tip closelyadjacent to its apex and to the separating zone.

A clear conception of the improved features constituting the presentinvention, and of the construction and operation of a typical cross-beltmagnetic separator embodying the same, may be had by referring to thedrawing accompanying and forming a part of this specification in whichlike reference characters designate the same or similar parts indilierent views.

Fig. l is a part sectional somewhat diagrammatic side view of a typicalcross-belt magnetic separator unit, looking longitudinally of the mainconveyor belt, and showing this belt and the supporting beams of theseparator in section; and

Fig. 2 is an enlarged transverse fragmentary section through thecross-belt separator, taken partially along the line 2-2 of Fig. l, butalso showing some of the elements in elevation.

While the invention has been shown and described as applied to only asingle cross-belt magnetic separating unit associated with the mainconveyor and as embodying an upper pole provided with but a singledepending wedge tip and which is formed entirely of ordinary magneticmaterial, it is not the intent to unnecessarily restrict the improvementto such a limited structure; and it is also contemplated that specificdescriptive terms employed herein be given the broadest possibleinterpretation consistent with the disclosure.

Referring to the drawing, the typical single cross-belt magneticseparating unit shown, comprises in general, an erectro-magnet having anupright magnetic loop 5 provided with lower and upper internal poles 6,7 respectively spaced apart to provide an intervening magnetic field gapor separating zone 8; a main endless con veyor 9 having an upperhorizontal mixed material transporting deck 10 extending transversely ofthe loop 5 through the zone 8 and coacting with the upper flat face 11of the lower pole 6; an auxiliary endless conveyor 12 having a lowerhorizontal magnetic particle removing deck 13 extending laterally of theloop 5 and across the deck 10 through the zone 8 and coactinglongitudinally with the apex 14 of the lower wedge projection or face 15of the upper pole 7; a magnetic material discharge hopper 16 mountedupon the loop 5 beneath the deck 13 and laterally beyond the separatingzone 8; and upper and lower annular magnet energizing coils or windings17, 18 respectively embracing the upper pole 7 and its pole face 15within the loop 5, the lower winding 18 being disposed closely adjacentto the wedge apex 14 and to the magnetic gap and having an increasingnumber of ampere turns approaching this apex.

The substantially rectangular upright magnetic loop 5 of theelectro-rnagnet may be supported upon channel bars 20 firmlyinterconnected by tie-rods 21, and the lower pole 6 rests directly uponthe bottom beam 22 of the loop while the upper pole 7 is suspendeddirectly from the top beam 23 of this loop. The upper deck 19 of themain endless belt conveyor 9 rests di rectly upon and is slidable acrossthe upper fiat face 11 of the lower pole 6, and this main conveyor 9coacts with end pulleys 24 also supported from the channel bars 20 andhas its lower run cooperable with transverse supporting rollers 25 whichare likewise journalled in bearings 26 mounted upon the frame bars 28.This main conveyor 9 may be driven in any suitable manner to cause itsupper deck to constantly transport a relatively thin layer of mixedmagnetic and non-magnetic material 27 through the separating zone 8 andbetween the two conveyor decks 10, 13 as illustrated in Fig. 2.

The lower run or deck 13 of the auxiliary endless belt conveyor 12directly engages and is slidable along the slightly rounded apex 14 ofthe lower wedge shaped projection or face 15 of the upper pole 7, andthis auxiliary conveyor 12 coacts with pulleys 29 journalled in bearings30 carried by the magnetic loop 5. One of the pulleys 29 may be drivenby an electric motor 31 also mounted upon the loop 5, and throughreduction gearing 32 and a belt drive 33, to cause the lower conveyordeck 13 to constantly advance through the separating zone 8 and towardthe magneticparticle discharge hopper 16, as depicted in Fig. l. 16which is also secured to and supported by the magnet loop 5, shouldextend along and beneath the lower deck 13 of the auxiliary conveyor 12closely adjacent to but laterally beyond the separating zone 8,, and thewindings 17, 18 which energize the entire magnet and which surround theupper pole 7 may be connected to any suitable source of electriccurrent.

When the improved cross-belt magnetic separator has een properlyconstructed as above described, its normal operation is as follows. Themagnet may be constantly electrically energized with the aid of thecoils 17, 18 to produce magnetic flux lines such as shown in dotand dashlines in Fig. 2, spanning the entire separating gap or zone 8 betweenthe poles 6, 7, and with the greatest concentration of flux at the wedgeapex 14 due to the formation of the coil 18 with an increasing number ofampere turns approaching the wedge apex. The conveyors 9, 12 should thenbe operated to continuously advance their cooperating decks, 10, 13respectively through the separating zone 8 as indicated by the arrows'in Figs. 2 and l. The mixture 27 of granular magnetic and non-magneticparticles should then be deposited in the form of a relatively thin anduniform layer upon the upper surface of the advancing lower deck 10 asit approaches the zone 8, and as the. layer of material passes throughthe magnetic gap the magnetic particles are withdrawn from the mixtureand are deposited upon the lower face of the advancing upper conveyordeck 13 while the non-magnetic particles are transported out of theseparating zone 8 by the deck 10. The with-v drawn magnetic particleswill adhere to the upper deck 13 until they are carried out of the zoneof magnetic influence and then drop by gravity into the discharge hopper16. The separation is thus effected continuously and automatically withthe greatest concentration along the apex 14 of the wedge shaped poleface or tip 15 and while the upper windings 17 produce the major por denof the energization of the magnet the gradually 'increasing number ofampere turns introduced by the tip embracing winding 18 are veryimportant for se eral specific reasons.

The improved placement or provision of the. gradually increasing numberof ampere turns inthe coil or winding 18 as it approaches the separatingnone, serves to most effectively concentrate the flux lines withi n.the, area C along the entire length of the wedge, apex 14, and it alsoacts as a partial magnetic shield or insulator amines The hopper whichprevents excessive leakage losses and results in increased fieldstrength. These advantages are'obtainable whether the pole tip is formedor ordinary metal throughout or whether it is constructed with a specialcobalt alloy tip, since the concentration of flux lines improves thelifting force which is proportional to the field strength and to thegradient of field strength available in each flux tube. It has beenfound in actual practice, that the use of the winding 18 embracing thewedge tip 15 of the letting pole 7 vastly improves the ability toseparate and pick up feebly magnetic particles and to thereby increasethe amount of magnetic material extracted, and since the cross-beltmagnetic separator is primarily adapted to handle ore embodying suchparticles the invention is especially adapted for application to suchmachines. The improved structure can be manufactured at moderate cost,and has proven highly satisfactory and successful in actual commercialuse.

It should be understood that it is not desired to limit this inventionto the exact details of construction of the cross-belt magneticseparator unit herein shown and described, for various modificationswithin the scope of the appended claims may occur to persons skilled inthe art.

I claim:

1. In a cross-belt magnetic separator, a main conveyor deck constantlymovable to transport mixed magnetic and non-magnetic particles in onedirection along a definite path, a magnet pole having a flat faceextending locallyacross said path beneath said deck, an auxiliaryconveyor deck spaced from. the top of said main deck and movabl acrosssaid path above said flat pole, a complementary magnet pole above saidauxiliary deck having at least one depending wedge projection extendingacross said path and cooperating through said decks with said fiat poleface to liftmagnetic particles from said mixture onto the. bottom of theauxiliary deck, and an electric energizing coil for said magnet polessurrounding said wedge projec tion closely adjacent to said auxiliarydeck and having an increasing number of ampere turns approaching thewedge apex.

2. In a cross-belt magnetic separator, a main conveyor deck constantlymovable to transport mixed magnetic and non-magnetic particles in onedirection along a definite path, a. magnet pole. having a flat faceextending locally across said path beneath said deck, an auxiliaryconveyor deck spaced from the top of said main deck and movable acrosssaid path above said flat pole, a complementary magnet pole above saidauxiliary deck having a depending wedge-shaped face extending across.said path and cooperating through said decks with said fiat pole faceto. lift magnetic particles from said mixture onto the. bottom of theauxiliary deck, and an electric energizing coil for said magnet polesembracing said wedge-shaped pole face closely adjacentto thev apex ofthe wedge and having. an increasing umb r f ampere rns. wa hins a dwedge. apex.

3. In a cross-belt magnetic separator, a main conveyor deck constantlymovable to transport mixed magnetic. and non-magnetic particles in. onedirection along a definite, path, a magnetic loop surrounding said deckand being provided with an inner lower magnet pole having a flat faceextending locally across said path beneath said deck, an auxiliaryconveyor deck spaced from the top of said main deck and movable acrosssaid path above said flat pole, an upper magnet pole associated with anddisposed within said loop above said auxiliary deck and having at leastone, wedge-shaped face extending across said path and cooperatingthrough said decks with said fiat pole face to lift magnetic particlesfrom said mixture onto he bq t rn. t he il a e k d ctri es sin ns c l; aaid 0p, d; a d. P916 having ab t on ofgraduallyincreasing amperev turnsapproaching and surrounding said wedge-shaped. pole face closelyadjacent to the apex of the. wedge.

4. In a cross-belt magnetic separator, an upright magnetic loop, a mainconveyor deck constantly movable to transport mixed magnetic andnon-magnetic particles through said loop in one direction along adefinite path, a magnet pole mounted upon the bottom of said loop andhaving a fiat face extending locally across said path beneath said deck,an auxiliary conveyor deck spaced from the top of said main deck andmovable across said path above said fiat pole, a complementary magnetpole suspended from the top of said loop above said auxiliary deck andhaving a wedge-shaped face extending across said path and cooperatingthrough said decks with said flat pole face to lift magnetic particlesfrom said mixture onto the bottom of the auxiliary deck, and an electricenergizing Winding for said loop and said poles having a portion ofgradually increasing ampere turns approaching and embracing saidwedge-shaped pole face directly adjacent to said auxiliary deck so as toconcentrate the magnetic flux at the apex of the wedge.

5. In a cross-belt magnetic separator, an upright magnetic loop, a mainconveyor deck constantly movable through said loop to transport mixedmagnetic and nonmagnetic particles along a definite path, a magnet poleWithin said loop having a flat face extending locally across said pathbeneath said deck, an auxiliary conveyor deck spaced from the top ofsaid main deck and movable laterally of said loop across said path abovesaid flat pole, a complementary magnet pole within said loop above saidauxiliary deck and having a depending wedge face extending across saidpath and cooperating through said decks with said fiat pole face to liftmagnetic particles from said mixture onto the bottom of the auxiliarydeck, and an electric energizing coil for said magnet poles surroundingand having a gradually increasing number of ampere turns approachingsaid wedge projection closely adjacent to said auxiliary deck.

6. In a cross-belt magnetic separator, an upright magnetic loop, a mainconveyor deck constantly movable to transport mixed magnetic andnon-magnetic particles through said loop along a definite path, a lowermagnet pole within said loop having a fiat face extending locally acrosssaid path beneath said deck, an auxiliary conveyor deck spaced from thetop of said main deck and movable across said path above said fiat pole,a complementary upper magnet pole suspended from said loop above saidauxiliary deck and having a depending wedge-shaped face extending acrosssaid path and cooperating through said decks with said flat pole face tolift magnetic particles from said mixture onto the bottom of theauxiliary deck, and an electric energizing coil for said magnet polesembracing and having a gradually increasing number of ampere turnsapproaching said wedge-shaped pole race closely adjacent to the apex ofthe wedge.

7. In a cross-belt magnetic separator, a main conveyor deck constantlymovable to transport mixed magnetic and non-magnetic particleshorizontally, a magnet pole having a flat face extending locally acrosssaid path and coacting with the bottom of said deck, an auxiliaryconveyor deck spaced from the top of said main deck and movablehorizontally across said path, a complementary magnet pole above saidauxiliary deck having a depend ing Wedge shaped face extending acrosssaid path and provided with an apex coacting longitudinally with the topof said auxiliary deck, and an electric energizing coil for said magnetpoles surrounding and having an increasing number of ampere turnsapproaching the apex of said wedge projection closely adjacent to saidauxiliary deck.

8. In a cross-belt magnetic separator, a main conveyor deck constantlymovable to transport mixed magnetic and non-magnetic particles along adefinite path, a magnet pole having a flat face extending across saidpath and coacting with the bottom of said deck, an auxiliary conveyordeck spaced from the top of said main deck and movable across said path,a complementary magnet pole above said auxiliary deck having a dependingwedgeshaped face the apex of which coacts longitudinally with the top ofsaid auxiliary deck, and an electric energizing coil for said magnetembracing said complementary pole and having an increasing number ofampere turns approaching the apex of said wedge-shaped pole face closelyadjacent to the apex of the Wedge.

References Cited in the file of this patent UNITED STATES PATENTS686,889 Daggett Nov. 19, 1901 2,321,356 Berman June 8, 1943 2,591,121Blind Apr. 1, 1952 2,591,122 Blind Apr. 1, 1952 FOREIGN PATENTS 109,233Germany Mar. 12, 1900

